1. Field of the Invention
The present invention relates to an ultrasound treatment system for coagulating or resecting the region of a living tissue to be treated.
2. Description of the Related Art
In recent years, it has become a matter of common practice that an endoscope is inserted in a body cavity in order not only to observe an organ in the body cavity but also to conduct various kinds of curative procedures and treatments under the observation through the endoscope.
A means for conducting a curative treatment under endoscopic observation includes an ultrasound aspiration system that utilizes ultrasonic vibrations for aspiration and an ultrasound knife system that utilizes ultrasonic vibrations for incision or the like. Moreover, there is a cautery knife system that applies a high-frequency signal to a living tissue through the tip of a probe for the purpose of incision or the like.
For example, Japanese Patent Laid-Open No. 62-127042 describes that a stone is clamped and crushed by means of ultrasonic vibrations. Japanese Patent Laid-Open 1-232944 describes that a living tissue is clamped and immobilized using clamp forceps and incised by a probe making ultrasonic vibrations. Japanese Patent Laid-Open No. 1-232945 describes that a living tissue is sucked for immobilization and then incised by a knife making ultrasonic vibrations.
Furthermore, Japanese Patent Laid-Open No. 1-232948 describes that ultrasonic vibrations are imposed on cutting forceps for efficient resection of a living tissue. Japanese Patent Laid-Open No. 1-232949 describes similarly to the Japanese Patent Laid-Open No. 1-232944 that a living tissue is immobilized using a clamping means and then treated by means of a treatment member on which ultrasonic vibrations are imposed. U.S. Pat. No. 5,322,055 has proposed an ultrasound surgical appliance shown in FIG. 1. The ultrasound surgical appliance has a holding member 991 attached to the tip of a sheath 990 at a point. A bar 992 lying through the sheath 990 is used to cause the holding member 991 to pivot. An ultrasound probe 993 is inserted in the sheath 990 so that the ultrasound probe 993 can turn about an axis. The ultrasound probe 993 has a knife-like incision area 994 formed on one side of the distal portion thereof, and has a substantially round coagulation surface 995 formed on the other side thereof. When the ultrasound probe 993 is turned by manipulating the appliance at a proximal position of the appliance, the incision area 994 or coagulation surface 995 is selected. Thus, the appliance has a composite structure.
To be more specific, for ultrasonic coagulation of a living tissue, as shown in FIG. 1, setting is such that the coagulation surface 995 is oriented toward the holding member 991. The living tissue is clamped by the holding member 991 and coagulation surface 995 and then subjected to ultrasonic coagulation. By contrast, for incising a living tissue, setting is such that the incision area 994 is oriented toward the holding member 991. The living tissue is clamped by the holding member 991 and incision area 994 and subjected to ultrasonic incision. Thus, one ultrasound surgical appliance is used to conduct ultrasonic coagulation and ultrasonic incision selectively.
In the ultrasound surgical appliance, one side of the distal portion of the ultrasound probe 993 exposed from the tip of the sheath 990 is the coagulation surface 995 having a substantially circular and blunt contour. The opposite side thereof includes the incision area 994 having a sharp contour suitable for incision. As shown in FIG. 1, during coagulation, in particular, since the sharp blade section is oriented in a direction opposite to an object tissue or is facing outward opposite to the holding member 991, there is a possibility that not only a burn but also an injury of a tissue by the blade section may occur. For avoiding these incidents, time-consuming and annoying check work is needed. This becomes one of causes deteriorating maneuverability.
Moreover, in the ultrasound surgical appliance, the clamp unit and surgical blade are used to clamp a tissue. This poses problems that a clamped area is limited and sufficient force is not applied to a region to be cut out.
In particular, for example, as far as a ligament containing lots of fibers is concerned, there is a problem that the ligament cannot be cut off reliably, or a problem that since it takes much time to perfectly cut off the ligament, a surgical blade may dissipate heat very much to burn any other living tissue in contact with the surgical blade.
As far as existing treatment appliances used for a surgical procedure under endoscopic observation are concerned, a treatment unit used to treat a living tissue is usually located at the distal end of a sheath that is an insertion unit for inserting the treatment unit into a living body, and a manipulating means for use in manipulating the treatment unit is located at the proximal end of the insertion unit.
In these treatment appliances for surgery under endoscopic observation, a structure, in which as described in DE G92 14059.9 or U.S. Pat. No. 5,290,308, an insertion unit and a treatment unit can be turned relative to a manipulating means, is well-known. According to Japanese Patent Laid-Open No. 6-167728 or DE G91 14 306.3, a frictional means is used to adjust a torque. Japanese Examined Patent Publication No. 5-86223 describes that a ball click is used to fix an angle of a turn.
As mentioned above, when an ultrasound treatment appliance is used to clamp a living tissue, it is essential to isolate a probe from a sheath or the like in terms of vibrations because of the presence of a transducer unit. Since there is a structural restriction that the probe cannot be turned because the center axis of the probe does not align with the center axis of a conveying means, an ultrasound treatment appliance in which a treatment unit can be turned freely relative to a manipulating means is unavailable. Depending on the situation of a living tissue, a hand handling a manipulating means may be obliged to be twisted or to handle the manipulating means in any other unnatural manner. Thus, the ultrasound treatment appliance still has drawbacks that must be overcome for practical use.
For resolving these drawbacks, making better approaches to a living tissue, and improving maneuverability, Japanese Examined Utility Model Publication No. 6-6809 has revealed that an insertion unit of an ultrasound treatment appliance is curved. However, in this appliance, since a handpiece serving as a manipulating means is circular and devoid of directivity, good maneuverability is ensured. In an ultrasound treatment appliance having a directive handle as a manipulating means, the aforesaid problems cannot be solved completely.
Furthermore, when an ultrasound treatment appliance is cleaned and sterilized, each component must be cleaned and sterilized with the greatest care. This work is quite laborious and cumbersome. For omitting the labor, the appliance may be designed to be disposable. However, there is a problem, which must be solved, concerning the reduction of medical expenses, diminishment of polluted wastes, and saving of resources. If any one part should be broken, the whole appliance would have to be repaired or replaced with a new one.
Furthermore, for example, the first related art described in Japanese Patent Laid-Open No. 60-80446 is an ultrasound surgical system that has the capability of a cautery knife so as to crush a living tissue using ultrasonic waves, and that feeds a high-frequency current to a horn at a distal end so as to arrest bleeding through part of a vessel. By handling switches, ultrasonic waves can be supplied or a high-frequency current can be fed.
Moreover, for example, the second related art described in Japanese Patent Laid-Open No. 60-227748 is a disclosure of an appliance that is a combination of the capability of an ultrasound knife with that of a cautery knife.
In this second related art, an effort is made to wield the outputs of the ultrasound and cautery knives simultaneously.
However, the appliance becomes large in size and expensive. The cautery knife has the hazard of a leakage current. It must be avoided that the hazard is intensified by combining the cautery knife with the ultrasound knife. Moreover, since the cautery knife and ultrasound knife are different from each other in terms of medical functions and advantages, they may not sometimes be acted simultaneously.
Additionally, the ultrasonic coagulation/incision system disclosed in the U.S. Pat. No. 5,322,055 oscillates with a living tissue clamped using the distal part of the probe and the clamping member. Resultant ultrasonic vibrations are transmitted to the probe, whereby a living tissue is coagulated or incised. If a large amount of blood or a fatty tissue is present in a surgical region, the blood or fatty tissue may be sucked into the sheath shielding the probe.
A driving mechanism for driving the clamping member is incorporated in the sheath of the ultrasonic coagulation/incision system. When compared with an ultrasonic suction apparatus having a very simple intra-sheath structure, the intra-sheath structure of the ultrasonic coagulation/incision system is very complex. Once blood or a fatty tissue sucked into the sheath adheres to the inside of the probe, it is very hard to remove the blood or fatty tissue.
When blood or a fatty tissue adheres to the inside of the probe, the impedance of the probe rises outstandingly. Consequently, the ultrasonic coagulation/incision system fails to ultrasonically oscillate. Specifically, the impedance characteristic of the probe is disordered, and the resonant frequency of a resonant circuit becomes uncertain. This poses a problem in that the ultrasonic coagulation/incision system cannot ultrasonically oscillate any longer.
In this type of ultrasonic coagulation/incision system, a living tissue to be coagulated and resected is clamped by the distal part of the probe and the clamping member. When the living tissue is clamped and immobilized, energy of ultrasonic vibrations is converted into frictional heat. The living tissue is gradually coagulated and then resected.
At this time, the frictional heat should merely be transmitted to a clamped portion of the living tissue. In practice, however, the frictional heat is dispersed over a plane on which the living tissue is clamped. There is a fear that a living tissue other than the intended living tissue may be affected by the heat.
For example, a nervous tissue is a region in which a problem may stem from transmission of heat. It is a matter of common practice that when treatment is conducted using the foregoing ultrasonic treatment appliance near the nervous tissue, the ultrasonic treatment appliance is separated by at least a certain distance from the region.
However, a region that must not be affected by heat may be sunk in a fatty tissue or hidden behind a treatment portion. In this case, the region may not be able to be observed. Furthermore, if a region susceptible to heat and the treatment portion are located mutually closely, ultrasonic treatment cannot be conducted. This poses a problem in that usable ultrasonic treatment appliances are limited.
Another problem will be described below. When the probe of the ultrasonic coagulation/incision system is vibrated ultrasonically, it may oscillate at a frequency other than predetermined frequencies (referred to as transverse vibration). In this case, an unbearable abnormal sound may be heard. Furthermore, in this mode, energy causing longitudinal vibration that is a normal oscillation form is converted into energy causing transverse vibration. This leads to a reduction in vibrational energy to be applied to the distal end of the probe. Eventually, deterioration in the functions of coagulation and incision is invited.
Furthermore, when the ultrasonic coagulation/incision system is used, mist is generated from the distal part thereof for clamping a living tissue and coagulating and for resecting it with ultrasonic vibrations. The mist clouds the interior of a body cavity during a surgical procedure under endoscopic observation. This hinders observation of a surgical field. Moreover, the endoscope itself is clouded. This poses a serious problem.
Furthermore, when the ultrasonic coagulation/incision system is used, as long as a blood vessel to be treated or an organ is exposed to the surface, no problem occurs. However, the organ may be sunk in a fatty tissue or the like, the organ may adhere to another region, or the treatment portion may be hidden behind a liquid such as blood. In this case, the region to be treated must be peeled and exposed beforehand. Various forceps or the like may therefore be used. An ultrasonic suction apparatus may be used to perform suction or any other treatment by taking a sufficiently long time. After the region to be treated is peeled and exposed, the ultrasonic coagulation/incision system is used to carry out the work of coagulation and hemostasis. However, especially in the field of surgery to be conducted under endoscopic observation, the work coagulation and hemostasis brings about the necessity of putting or removing a plurality of tools using a trocar and cannula. Otherwise, a plurality of operators must work in cooperation with one another. This is time-consuming. Since the work cannot be carried on continuously, a long time is required for a surgery. Besides, a patient load is enormous.